This invention relates to improvements in bullets and other projectiles for firing, launching, dropping and otherwise propelling against various targets, and more particularly to projectiles that perform exceptionally in the barrel of a gun and on impact with a variety of target materials without the usual deleterious effects on the projectile or the gun barrel normally experienced with use of conventional projectiles.
Since the turn of the century when jacketed ammunition was invented, most modern ammunition has used bullets that have a lead core and a jacket of a stronger but still soft metal such as copper, brass or bronze. The purpose of the jacket is to contain the lead core to minimize the shedding of lead particles during passage through the rifle bore and to hold the bullet together on impact with the target so that it does not break into multiple fragments as unjacketed bullets tend to do. The physiological shock effect of an intact bullet on an animal is much greater than a multitude of bullet fragments, and the penetration capability of an intact bullet is also much greater than individual bullet fragments.
Even fully jacketed bullets lack sufficient strength to penetrate significant thicknesses of most ordinary materials such as wood, and are almost worthless against steel and masonry because the bullet expands greatly on impact and dissipates its energy over such a wide area that it has little penetrating ability. A bullet that could be fired through trees to hit deer and enemy soldiers would be a valuable addition to the tools of a hunter and the Armed Forces, respectively, and a bullet that could be fired through building materials to hit concealed gunmen and snipers would be extremely valuable to the police and Armed Forces who must fight in urban environments.
Much research has been expended in recent years to develop a penetrating warhead that is capable of penetrating great depths of loose rounded rock and gravel and then penetrating a hardened reinforced concrete bunker. The location of these targets is often known precisely, and the guidance and control technology is available to guide the bomb or missile accurate to the target, but the simple expedient of burying the bunker under many yards of loose rounded rock and gravel protects it against most known weapons because of the ability of the overburden to absorb and divert the projectile so that it misses the bunker, or loses the energy to penetrate it. A projectile that is capable to penetrating straight through the rounded rock overburden, and then penetrate the hardened bunker and destroy it, would be a valuable addition to the arsenals of the armed forces.
The case of conventional ammunition has long been considered a necessary but troublesome element of ammunition. It is expensive to make and then collect after firing to resize and reload. In some applications, the ejection of spent cartridge cases actually poses a danger to the gunner, especially in fighter aircraft wherein the danger of ingestion of cartridge cases into the jet engine of the fighter could cause serious damage to the engine. If a cartridge were available that did not use a case, so that the entire cartridge formed the projectile and no part of the structure was wasted, the efficiency and effectiveness of the armed forces would be substantially improved. Moreover, this type of ammunition would benefit the civilian market as well by eliminating the need to collect the spent cartridge cases in firing ranges and eliminating long duration litter in the wilderness caused by hunters who do not bother to retrieve their spent cartridge cases.
Accordingly, it is an object of this invention to provide an improved projectile for being propelled through the bore of a gun barrel, a projectile that passes through the bore cleanly without shedding particles or depositing projectile material in the bore of the gun.
Another object of this invention is to provide a bullet that offers improved penetration and enhanced damage to target animals.
A further object of this invention to provide an improved projectile that remains intact on impact with the target and concentrates its full energy in the region of impact.
A yet further object of this invention to provide an improved projectile that has greatly improved penetration capabilities over conventional armor piercing bullets.
A still further object of this invention to provide an improved bullet that can penetrate steel armor in a straight line and cause massive spalling and a torrent of metal shrapnel on the inside surface of the metal target.
Another still further object of this invention is to provide an improved projectile capable of deeper penetration of stone, brick, wood, concrete, and loose rock than prior art projectiles.
Still another object of this invention to provide an improved bullet for firearm ammunition that has a much higher muzzle velocity than conventional bullets, and a flatter trajectory over all but the longest ranges, resulting in much improved accuracy.
It is yet another object of this invention to provide an improved caseless ammunition that can be used in conventional firearms.
These and other objects of the invention are attained in a projectile of shape memory alloy such as Nitinol in its martensitic state. The projectile may be solid Nitinol or may be a shell partially filled with a denser material such as lead, tungsten or uranium. The Nitinol shell may function as both bullet and case in a caseless ammunition system in which the shell contains a propellant which is sealed in the shell by an apertured end closure containing a primer. The caseless ammunition can be used in conventional firearms adapted with an insert.